Process for producing leather with the assistance of iron salts



UNITED STATES PATENT OFF-16E.

OTTO ROHM, 0F DARMSTAIDT, GERMANY.

PROCESS FOR PRODUCING LEATHER WITH THE ASSISTANCE IRON SALTS.

No Drawing. Application filed March 10, 1917,

To all whom it may concern Be it known that I, Or'ro RUHM, a citizen ofGermany, residing at No. 4-4} l/Veiterstiidterstrasse, in the city ofDarmstadt, Grand Duch of Hessia, German Empire, have invented anImprovement in Processes for Producing Leather with the Assistance ofIron Salts; and I do hereby declare that the following is a full, clear,and exact description of the same.

. According to the process set forth inmy patent application Serial No.154,083, ferric iron salts are used to produce leather-by allowingaldehyde, preferably formaldehyde, said iron salts being preferablybasic ferric iron chlorid, to act on the skins. This iron and aldehydetanning process can also be combined with a treatment of the skins withneutralizing or iron precipitating substances, such as ammonia, alkalis,alkaline salts or with phenols, naphthols, organic carbon acids,vegetable tanning substances, or with soaps, sulfids, polysulfids or thelike.

Now it has been found that the advantages of a combined aldehyde andiron tanning process are also obtained if the aldehyde tanning processis carried out simultaneously with, or even after, the neutralizing ofthe leather, subsequent to the metal tanning, has been effected. If thealdehyde treatment is carried out sii'nultaneously with the neutralizingprocess the further advantage is obtained that the warping of the grainwhich otherwise occurs is avoided, and a specially fine, intricate andvery durable grain is obtained.

Example: 100 parts depilated skins are worked 1 to 2 hours with 200.)arts water-Hi parts of 40% formaldehyde solution+2 parts of sodiumbicarbonate. The skins are then washed with water and with 2/3 basicferric iron chlorid in doses of 1()2()% until the desired quantity ofiron has been taken up, all as set forth-in my copendi'ng applicationabove noted. I

In carrying out this improved process, the skins .treated as specifiedare subjected to a further treatment with 2% formaldehyde which is usedsimultaneously with the neutralizing process effected with 1 to 3% soda,

Specification of Letters Patent.

' Patented Jan. 4, 1921.

Serial No. 154.034. Renewed May 28, 1920. Serial No. 385,065.

preferably sodium bicarbonate, according to the strength of the tanningextract.

Further advantages have been obtained when the tanning is carried outwith a mixture of various metal salts. In doing so leather is obtainedhaving new. properties. While common iron leather, for example, shrlnkstogether in water of but 60 (1., and a leather tanned with ferric ironsaltand aldehyde shrinks at about 90 0., a mixed ta'nnlng, firstly withchrome salt. and then with ferric iron salts, yields a leather which isstable when boiled and is also fuller and heavier than common chromeleather.

What I claim and desire. to secure by Letters Patent of the UnitedStates is 1 The process for producing leather, which consists in tanningthe skins with ferric iron salts, followed by a neutralization withferric iron compound precipitating substances and a treatment withaldehydes.

2 The process for producing leather which consists in tanning the skinswith basic ferric iron chlorid followed by a neutralization with ferriciron compound precipitat- Lug1 substances and atreatment with aldey es.

3 The process for producing leather whlch consists in tanning the skinswith ferric iron salts followed by a neutralization with alkalis and atreatment with aldehydes.

4. The process for producing leather which consists in tanning the skinswith ferric iron salts followed by a neutralization with sodiumbicarbonate, and a treatment with aldehydes.

5. The process for producing leather which consists in tanning the skinswith ferric iron salts followed by a neutralization with iron compoundprecipitating substances and a treatment with formaldehyde.

6. The process for producing leather which consists in tanning withferric iron salts followed by a neutralization with iron compoundprecipitating substances and a simultaneous treatment with aldehydes.

7. The process for produding leather which consists in tanning the skinswith basic ferric iron chlorid followed by a neutralization with 1 t0 3%sodium bicarbonate and a simultaneous treatment with 2%- formaldehyde. 1

8. The process for producing leather 5 which consists in tanning theskins with ferric iron salts and with other metal salts followed by atreatment with aldehydes.

()TTO RoHM.

